1. Field of the Invention
The present invention relates to a network receiver, and more particularly, to a network receiver complied with high definition multimedia interface (HDMI) version 1.4 and the control method thereof.
2. Description of the Prior Art
The HDMI version 1.4 has a new function named HDMI Ethernet and Audio return Channel (HEAC), where the HEAC function can make a network receiver to transmit/receive HDMI Ethernet Channel (HEC) data and Audio Return Channel (ARC) data simultaneously. Therefore, complex home network wiring can be simplified to provide a single high bandwidth and high-quality wiring in order to transfer complete images, audio, and Ethernet transports, and achieve integration of multimedia networking applications.
In the HDMI device having HEAC function, both the HEC data and the ARC data are transmitted via two transmission lines, where the transmitted HEC data is a differential mode signal, and the transmitted ARC data is a common mode signal. Ideally, an impedance of each of the two transmission lines should be 50 ohm that is defined in HDMI specification, and the HEC data can be obtained by calculating a difference between two signals of the two transmission lines at receiving ends to cancel the common mode signal. However, referring to a common mode signal shown in FIG. 1, if the transmission lines (TX+, TX−) used to transmit HEC data and ARC data have poor quality, that is their impedances may not be the same or the impedances of the transmission lines do not match the impedances of the receiver, the amplitudes of two-halves of the received common mode signals may be different. The two-halves of the common mode signal having different amplitudes will result in a generation of an unwanted differential mode signal, and this unwanted differential mode signal will influence the quality of the HEC data.